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Edition No. 8 June 1996
DNA and Protein Exposed to Modulated RF Fields

Prof. Dr. W. Rüger, Ruhr-Universität Bochum, Fakultät für Biologie, AG Molekulare Genetik (Part One)
Prof. Dr.-Ing. V. Hansen, Universität-GHS-Wuppertal, Lehrstuhl für Theoretische Elektrotechnik (Part Two)


There is increasing discussion on biological damage in organisms that had been exposed to electromagnetic radiation. Exposures of men to electromagnetic fields are connected with modern life and practically these exposures, as e.g. caused by TV, radio and mobile telephones, cannot be avoided. However, there are fears that these exposures might cause mutations and induce cancer.

For many reasons, procaryotic organisms are useful in tracing biological damage inflicted by physical or chemical agents. Therefore, we designed simple experiments that should allow to test the effects of electromagnetic fields on biological material. Since damages as mentioned above, often occur at that level of DNA or of proteins binding to DNA, we designed simple experiments with the aim to test whether DNA or proteins may be damaged if exposed to an electromagnetic field. All samples were exposed in a waveguide as described above in volumes of 0,1 ml, with the exception of the agar plates applied in the mutagenicity experiments.

Thus, we tested the survival of bacteriophages over a total exposure time of three months and we did not find any reduction of the survival as compared to control phages which had not been exposed but remained under otherwise unchanged conditions. The conclusions drawn from these results are, that neither the DNA nor the sensitive proteins of this virus were damaged in the electromagnetic field.

Likewise, we have exposed closed circular DNA. The introduction of single or double strand breaks would become visible after electrophoresis on polyacrylamide gels by changing the migration velocity. No differences were observed among samples exposed to the electromagnetic field as compared to controls outside the field.

Further we tested mutagenicity of four bacterial strains, lacking different DNA repair mechanisms. No increased mutagenicity was observed during a one week exposure to the electromagnetic field.

Following the ideas that electromagnetic radiation might damage or change hydration of macromolecules we tested as to whether DNA exposed to an electromagnetic field was partially denatured. But also in these experiments no shifts in the optical densities could be observed with the samples exposed in a waveguide and unexposed controls. Also, the kinetics of the enzyme ß-galactosidase remained identical in samples exposed to the field and unexposed controls.

Since no detectable damage could be detected in the experiments described above, we conclude that the electromagnetic fields over the time applied in our experiments, do not induce damage to DNA or proteins in general.


The main components of the test assemblies for exposing the biological material to modulated radio frequency radiation are two rectangular hollow waveguides. They were designed for fundamental mode operation (TE01-mode) with low standing wave ratios at frequencies around 900 MHz (cut-off frequency fC = 606 MHz) and 1750 MHz (fC = 1158 MHz), respectively. Detailed technical data of the waveguides and the measured reflection and transmission coefficients are given.

Up to 30 test tubes containing 0.1 cm3- 1 cm3 of the culture medium were placed into the waveguides. They were exposed to RF power of levels typically used in mobile communication systems. In order to verify the achievement of welldefined, reproducible and substantially uniform exposures of the culture medium extensive numerical calculations were also performed. The electrical properties of the biological material were determined by measurements.

The distributions of the electromagnetic field strengths and values of the specific absorption rates are given for different arrangements of the test tubes inside the waveguides.

It must be emphasized, however, that every change of the arrangement or volume of the culture medium as well as the use of other containers may cause drastical changes of the electromagnetic field distributions and the radiation exposures.

To fulfill the specific requirements of the photometric measurements a parallel-plate waveguide was built up which provides a pure propagating TEM-wave and a homogeneous exposure of the material under test. The design criteria are discussed in detail.

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